Cocoon shock, X-ray cavities and extended Inverse Compton emission in Hercules A: clues from Chandra observations

Abstract

We present a detailed analysis of jet activity in the radio galaxy 3C348 at the center of the galaxy cluster Hercules A. We use archival Chandra data to investigate the jet-driven shock front, the radio-faint X-ray cavities, the eastern jet, and the presence of extended Inverse Compton (IC) X-ray emission from the radio lobes. We detect two pairs of shocks: one in the north-south direction at 150 kpc from the center, and another in the east-west direction at 280 kpc. These shocks have Mach numbers of $\mathcal{M}=1.65\pm 0.05$ and $\mathcal{M}=1.9\pm 0.3$, respectively. Together, they form a complete cocoon around the large radio lobes. Based on the distance of the shocks from the center, we estimate that the corresponding jet outburst is 90-150 Myr old. We confirm the presence of two radio-faint cavities within the cocoon, misaligned from the lobes, each $\sim$100 kpc wide and 40-60 Myr old. A backflow from the radio lobes might explain why the cavities are dynamically younger than the cocoon shock front. We also detect non-thermal X-ray emission from the eastern jet and from the large radio lobes. The X-ray emission from the jet is visible at 80 kpc from the AGN and can be accounted for by an IC model with a mild Doppler boosting ($\delta \sim 2.7$). A synchrotron model could explain the radio-to-X-ray spectrum only for very high Lorentz factors $\gamma \ge 10^8$ of the electrons in the jet. For the large radio lobes, we argue that the X-ray emission has an IC origin, with a 1 keV flux density of $21.7\pm 1.4\text{(statistical)}\pm 1.3\text{(systematic)}$ nJy. A thermal model is unlikely, as it would require unrealistically high gas temperature, density, and pressure, along with a strong depolarization of the radio lobes, which are instead highly polarized. The IC detection, combined with the synchrotron flux density, suggests a magnetic field of $12\pm 3\mu$G in the lobes.

arXiv commentAccepted for publication in Astronomy & Astrophysics

References in corpus (63)

• The chemical composition of the Sun
• Unified Schemes for Radio-Loud Active Galactic Nuclei
• Observational Evidence of AGN Feedback
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Heating Hot Atmospheres with Active Galactic Nuclei
• A Systematic Study of Radio-Induced X-ray Cavities in Clusters, Groups, and Galaxies
• Mechanical Feedback from Active Galactic Nuclei in Galaxies, Groups, and Clusters
• Intracluster Medium Entropy Profiles for a Chandra Archival Sample of Galaxy Clusters
• Magnetic Field in Clusters of Galaxies
• An Accurate Flux Density Scale from 50 MHz to 50 GHz
• The X-Ray Jet of PKS 0637-752: Inverse Compton Radiation from the Cosmic Microwave Background ?
• Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers
• An X-ray study of magnetic field strengths and particle content in FRII radio sources
• A High Resolution Study of the Hydra A Cluster with Chandra: Comparison of the Core Mass Distribution with Theoretical Predictions and Evidence for Feedback in the Cooling Flow
• Radio galaxies and feedback from AGN jets
• The cluster-scale AGN outburst in Hydra A
• Shocks and Cavities from Multiple Outbursts in the Galaxy Group NGC 5813: A Window to AGN Feedback
• The Dance of Heating and Cooling in Galaxy Clusters: 3D Simulations of Self-Regulated AGN Outflows
• Ultra-fast outflows in radio-loud active galactic nuclei
• Magnetic field strengths in the hotspots and lobes of three powerful FRII radio sources
• Linking Macro, Meso, and Micro Scales in Multiphase AGN Feeding and Feedback
• Evidence for AGN Feedback in Galaxy Clusters and Groups
• The powerful outburst in Hercules A
• High-energy particle acceleration at the radio-lobe shock of Centaurus A
• On the two main classes of Active Galactic Nuclei
• The X-ray Jets of Active Galaxies
• The spatial distributions of cooling gas and intrinsic X-ray absorbing material in cooling flows
• Hot Atmospheres, Cold Gas, AGN Feedback and the Evolution of Early Type Galaxies: a Topical Perspective
• The beaming pattern and spectrum of inverse Compton radiation in blazars
• Relativistic Doppler-boosted emission in gamma-ray binaries
• A multiband study of Hercules A. II. Multifrequency VLA imaging
• A Chandra detection of diffuse hard X-ray emission associated with the lobes of the radio galaxy 3C 452
• Thermodynamic perturbations in the X-ray halo of 33 clusters of galaxies observed with Chandra ACIS
• Magnetic field strengths in the hot spots of 3C33 and 3C111
• The Chandra view of extended X-ray emission from Pictor A
• Dissecting the turbulent weather driven by mechanical AGN feedback
• The Cocoon Shocks of Cygnus A: Pressures and Their Implications for the Jets and Lobes
• FR II radio galaxies at low frequencies I: morphology, magnetic field strength and energetics
• Spin-driven jet feedback in idealised simulations of galaxy groups and clusters
• Metal Abundances in the Cool-Cores of Galaxy Clusters
• Radio/X-ray Offsets of Large Scale Jets Caused by Synchrotron Time Lags
• AGN Feedback in Galaxy Group 3C 88: Cavities, Shock and Jet Reorientation
• The XMM-Newton Detection of Diffuse Inverse Compton X-rays from Lobes of the FR-II Radio Galaxy 3C98
• Discovery of an X-ray cavity near the radio lobes of Cygnus A indicating previous AGN activity
• Canonical Particle Acceleration in FRI Radio Galaxies
• Jets in radio galaxies and quasars: an observational perspective
• The dynamics of the giant radio galaxy 3C 457
• An X-ray survey of the 2Jy sample. II: X-ray emission from extended structures
• The Spectacular Radio-Near-IR-X-ray Jet of 3C 111: X-ray Emission Mechanism and Jet Kinematics
• Evidence of non-thermal X-ray emission from radio lobes of Cygnus A
• Origin of the ring structures in Hercules A -- Sub-arcsecond 144 MHz to 7 GHz observations
• Suzaku observation of the giant radio galaxy 3C 326
• A multiband study of Hercules A. I. ROSAT observations of the intracluster medium
• Detection of non-thermal X-ray emission in the lobes and jets of Cygnus A
• Multiple shock fronts in RBS 797: the Chandra window on shock heating in galaxy clusters
• First Results of the 74 MHz VLA-Pie Town Link. Hercules A at Low Frequencies
• The X-ray Ribs Within the Cocoon Shock of Cygnus A
• The X-Ray Cavity Around Hotspot E in Cygnus A: Tunneled by a Deflected Jet
• Hubble Space Telescope Observations of Dusty Filaments in Hercules A: Evidence for Entrainment
• Extended X-ray emission associated with the radio lobes and the environments of 60 radio galaxies
• On the large scale morphology of Hercules A: destabilized hot jets?
• First Dynamic Computation of Synchrotron Emission from the Cygnus A Radio Cavity; Evidence for Electron Pair Plasma in Cavity
• Magnetic fields and extraordinarily bright radio emission in the X-ray faint galaxy group MRC 0116+111

Cited by in corpus (1)

• Detection of Anisotropies in the Circumgalactic Medium of Disk Galaxies: Supermassive Black Hole Activity or Star Formation-driven Outflows?